DESCRIPTION: (Adapted from the Applicant's Abstract.) In the proposed study, techniques will be developed for short-term chronic recordings of different auditory response from puppies aged 3 days to 3 weeks. Cochlear microphonic, summating potential, cochlear nerve action potential, and brainstem auditory evoked potential will be recorded using electrodes surgically implanted on the round window 24-48 hours after birth. Auditory stimuli will be introduced through stimulus delivery tubing implanted on the tympanic membrane to bypass the sealed ear canal. Responses will be collected daily from beagle puppies to document normal developmental patterns. Dalmatians puppies bred from bitches with a history of producing many deaf offspring will be assessed by identical techniques to establish when the normal developmental process is altered. Histopathologic evaluations will be correlated with physiologic data.